1. Field of the Invention
This invention relates to a camera, and more particularly to a so-called preparatory winding type camera wherein, after a film as a whole in a patrone is previously wound up, one frame of the film is automatically delivered each time a shutter release is performed.
2. Description of the Related Art
The preparatory winding type camera of this type has previously been constructed in such a way that, after the whole film in the patrone is previously wound up, one frame is rewound, and one frame is rewound each time the shutter release is performed after the completion of the preparatory winding.
Furthermore, after the film in the patrone is wound up for a photographing prohibiting region ("S" of the film) during the preparatory winding processing, the number of film frames is counted up each time one frame is wound, and counted down each time one frame is rewound.
That is, during the preparatory winding processing, a motor for the film delivery is rotated in a direction of the preparatory winding ( normal rotation ), whereby the film winding is started. With this operation, a free sprocket interlocking with perforations of the film is rotated and, due to this rotation, pulse signals SO (pulse signals outputted by four pulses per film frame delivery) are generated. When the SO count value of the pulse signals SO reaches 14 as shown in FIG. 6, the count value of a film counter is counted up to "1", and thereafter, each time the SO count value is increased by four (each time one frame is wound), the film count value is counted up. Then, when the pulse signals SO are not generated by four pulses for a predetermined time (one sec.), it is judged that the film is wound up as a whole, whereby braking is applied to the motor for the film delivery. Subsequently, the motor for the film delivery is rotated reversely, whereby one frame is rewound, thus ending the preparatory winding processing. With this operation, the film count value becomes "N-1".
Thereafter, one frame of the film is rewound each time the shutter release is performed, and the film count value is counted down per frame delivery. Then, when the count value reaches "0", it is determined that photographing by the whole film is completed, and one frame delivery operation is continued, whereby the film rewinding is performed.
Incidentally, a liquid crystal display device (LCD) for displaying the number of film frames which can be photographed displays the film count value as it is.
Now, the reason why the film is rewound by one frame during the preparatory winding processing as described above resides in that such a disadvantage is eliminated that a portion of the film is cut away by laboratory equipment. During this rewinding, the film counter is counted down, whereby the number of film frames, which is displayed on the LCD is changed in display. As the result, the display of the film frames during the preparatory winding processing is subjected to up-down fluctuations, so that a lot of confusion has been given to users by the up-down fluctuations.